The present invention relates to removable lids for containers, and particularly to a lid for reclosing opened containers of carbonated beverages and the like.
Many beverages contain amounts of dissolved gases, principally carbon dioxide, which must be kept in solution by confining the gas together with the liquid and maintaining a certain amount of pressure on the beverage during its storage in such containers. Generally speaking, when temperature of a beverage increases at a constant pressure the solubility of gas in the liquid decreases, and the tendency of the dissolved gas to escape from the liquid increases correspondingly. On the other hand, if pressure of the gas is increased, solubility of the gas increases.
Much of the appeal of carbonated and other "sparkling" beverages is because of the presence of dissolved gases providing an effervescence which is pleasant, both visually and to the taste. However, once a container of such a beverage is opened, pressure is reduced and the temperature of the beverage is likely to increase. If the dissolved gases are free to evaporate and become separated from the beverage, the effervescence is lost and the beverage becomes "flat," losing its appeal and palatability. It is important, therefore, to provide a tight lid to cover a container for storing such a beverage in order to maintain pressure of the gas on the beverage, yet it is impractical to pour such a beverage from an ordinary opened beverage can into a different container provided with a screw-on top or the equivalent, because the mechanical agitation caused by pouring also causes the dissolved gases to escape from the solution.
Carbonated beverages, beer, ale, and many other drinks are now widely sold in thin-walled cans made of aluminum, with a sheet metal top which usually includes an easily operated can-opening device, usually including an easy-opener lever or pull tab riveted to the top, so that lifting the free end of the lever breaks free and depresses a weakly connected portion of the top, to create an opening. The opener lever, however, is close to the top surface, and not particularly easy to grasp to open the can.
The top is attached to the upper edge of the sidewall of such cans along a top rim including a crimped bead which physically connects the top to the sidewall with a gas-tight seal strong enough to contain the beverage and prevent the dissolved gases from escaping. Once such an easy-opening beverage can has been opened, however, the top of the can must be covered tightly to preserve pressure or the beverage will lose its effervescence within a few hours.
Molded plastic lids have for some time been available for the purpose of covering beverage cans. Such previously available beverage can lids include a generally flat circular top member and depending cylindrical sidewalls which fit snugly and elastically over and around the opened top of an ordinary beverage can. Some such covers have a series of cylindrical walls of increasing diameter interconnected by annular flat portions so that a single cover is useful with beverage cans having any of three different diameters, for example. Such lids, however, are not particularly effective in sealing a beverage can tightly enough to preserve effervescence by retaining dissolved gases in solution within a beverage. Such previously available beverage can lids either have permitted leakage of gas and failed to hold sufficient pressure to preserve the effervescence of the beverage, or else have been forced entirely off the top of the beverage can as a result of the pressure within becoming too great.
What is needed, then, is an improved lid for sealingly covering beverage cans, particularly cans containing carbonated and other effervescent beverages, in order to preserve the dissolved gas content of such beverages after the container has once been opened. It would also be advantageous if the lid included a device for gripping the opener lever portion of an easy-opening can.
Most beverage cans are manufactured to be easily stackable, and aluminum beverage cans, in particular, are commonly manufactured with a concave bottom and a bottom rim which is of smaller diameter than the diameter of the main body of the container, so that the bottom rim of such a can fits snugly within the top rim of a like can, facilitating stacking of such cans with a relatively small likelihood of top cans being displaced accidentally from atop lower cans. The previously available plastic lids for use on beverage cans, because of their generally flat top member, defeat the possibility of an upper can being nested within the rim of a bottom can, making it more likely that a can stacked upon a can covered by such a previously available lid can easily be dislodged and spilled.
What is further desired, then, is an improved lid for a beverage can which preserves the ability to stack similar cans atop a can covered by such a lid.
Although a lid for a beverage container needs to be secure enough to maintain the effervescent qualities of the beverage, it also needs to be removable without undue difficulty. Therefore, an improved lid for opened beverage cans must also provide for such removability.